# NASA-Funded Research Discovers Life Built With Toxic Chemical



## shy ♡ (Dec 3, 2010)

Hell to the fucking yes.



> This will change the way astrobiologists look for life on other planets, including where they look (arsenic-rich atmospheres were previously considered off-limits


Excuse me while I squee.


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## Blastoise Fortooate (Dec 3, 2010)

:)

This is cool.


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## opaltiger (Dec 3, 2010)

I still don't see why it's being treated as such a huge deal. Okay, yes, bacteria can do incredible things in toxic environments! This doesn't tell us much about where to look when so far our search has pretty much been limited to "water or no water".


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## shy ♡ (Dec 3, 2010)

opaltiger said:


> I still don't see why it's being treated as such a huge deal. Okay, yes, bacteria can do incredible things in toxic environments! This doesn't tell us much about where to look when so far our search has pretty much been limited to "water or no water".


Because our research doesn't have to be limited to those things anymore. (Not that it should have been before, honestly.)

Also, because it's totally frickin' cool.


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## Aisling (Dec 3, 2010)

I think arsenic is just the beginning, man. Who knows what else stuff could be substituting for phosphorous out there? The _sky's_ not even a limit anymore.


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## Green (Dec 3, 2010)

What next?


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## opaltiger (Dec 3, 2010)

> Because our research doesn't have to be limited to those things anymore. (Not that it should have been before, honestly.)


But... all this is telling us is "alien life could be really weird". Is this something we honestly didn't know before? Okay, so we can add "arsenic" to the list of elements that life can apparently develop in, but still. This is not earth-shattering; plenty of weird discoveries have been made before.

It's an incredible discovery for biochemists, but in terms of alien life it really isn't all that terribly interesting.


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## Butterfree (Dec 3, 2010)

So wait, the arsenic article wasn't clear. Do they actually substitute arsenic for phosphorus _in the DNA molecule_ itself?


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## opaltiger (Dec 3, 2010)

Bachuru said:


> So wait, the arsenic article wasn't clear. Do they actually substitute arsenic for phosphorus _in the DNA molecule_ itself?


That's the sense I got, but it is frustratingly vague. Which, like I said, really interesting! Just not any more interesting than, say, chemosynthesis. eta: Oh, wait: it's even less interesting! It wasn't even naturally occurring! All they really found was a bacteria that could tolerate reasonably high levels of arsenic, then they coerced it into growing in extremely high levels of arsenic, noticed an odd P/As ratio and assumed phosphorous had been replaced by arsenic.

So, basically, it's an extremophile. Of which there are lots. _And lots._


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## PK (Dec 3, 2010)

opaltiger said:


> That's the sense I got, but it is frustratingly vague. Which, like I said, really interesting! Just not any more interesting than, say, chemosynthesis. eta: Oh, wait: it's even less interesting! It wasn't even naturally occurring! All they really found was a bacteria that could tolerate reasonably high levels of arsenic, then they coerced it into growing in extremely high levels of arsenic, noticed an odd P/As ratio and assumed phosphorous had been replaced by arsenic.
> 
> So, basically, it's an extremophile. Of which there are lots. _And lots._


How did it feel choking the life out of my sense of wonder, opal?

*HOW DID IT FEEL*


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## Negrek (Dec 3, 2010)

For the most part opaltiger is right. It tends to be the way of scientists to say, "How interesting, we think we might have found that arsenic could replace phosphorous in the DNA backbone of this organism under certain circumstances." The popular press will then turn this into something like, "ZOMG ALIENSSSS!!!" It does at least appear to be a bit more promising than this:



> ...noticed an odd P/As ratio and assumed phosphorous had been replaced by arsenic


According to this news release here the procedure they used to look at the incorporation of phosphorous into the DNA was like this:



> The team used two different mass-spectrometry techniques to confirm that the bacterium's DNA contained arsenic, implying — although not directly proving —that the element had taken on phosphate's role in holding together the DNA backbone. Analysis with laser-like X-rays from a synchrotron particle accelerator indicated that this arsenic took the form of arsenate, and made bonds with carbon and oxygen in much the same way as phosphate.


In any case, this is pretty much how things go when it comes to science journalism. Scientific discoveries are typically pretty modest and more along the lines of "well it appears to be like..." than really earth-shattering and definite. While this paper is a pretty cool thing for biochemists, they hype it up quite a bit to try and make it more exciting for non-sciencey-types. While this is the first time (to my knowledge) that there's been an indication that an organism might be able to survive totally without phosphorous, it probably won't do a whole lot to impact our search for life on other planets or anything--it's just a confirmation of what was already widely suspected, that the elements almost universally required by life on this planet are not necessarily obligatory for _all_ life like what exists here on Earth. It's also pretty cool, and if it turns out the arsenic really is performing normal biological functions that phosphorous ordinarily would, there will be a ton of cool research opportunities looking at just how that works and how other substitutions might occur, etc.

I wish I could read the actual paper where they detail the actual methodology and findings, but somehow my university's online subscription to _Science_ is stupid and only covers content published three or more years ago. If I wander down to the library in the next few days or so, presumably the hard copy will have come in and I can read it then.

...ironically, I was supposed to be studying for my biochemistry test later this morning rather than writing this post.


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## Tarvos (Dec 3, 2010)

I suppose on Monday when I head for the TU I've got summat to look at.


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## opaltiger (Dec 3, 2010)

I just read the paper, and the evidence that arsenate replaced phosphate in DNA is more persuasive than I had thought, yeah.


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## Teh Ebil Snorlax (Dec 3, 2010)

When I first read about this, I was wondering why anyone thought this was a big deal in the search for alien life. It's a fucking huge discovery in the field of biochemistry but just because NASA helped fund it, people think its relevant to space.


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## Phantom (Dec 3, 2010)

^ people can be hopeful.


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## Lucas₇₅₅ (Dec 4, 2010)

So arsenic can be non-poisonous in DNA molecules?

Great, sodium does the same thing in table salt. Except not alive.


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## PK (Dec 4, 2010)

Lucas755 said:


> So arsenic can be non-poisonous in DNA molecules?
> 
> Great, sodium does the same thing in table salt. Except not alive.


... what is this i don't even


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## Lucas₇₅₅ (Dec 4, 2010)

PK said:


> ... what is this i don't even


The big deal people are making is that arsenic is normally poisonous, and it's now a building block of DNA for this bacteria. But strands of DNA, correct me if I'm wrong, are actually molecules. I'm saying that sodium, a poisonous element by itself, does the same thing in table salt, something you can eat without dying.


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## PK (Dec 4, 2010)

Lucas755 said:


> The big deal people are making is that arsenic is normally poisonous, and it's now a building block of DNA for this bacteria. But strands of DNA, correct me if I'm wrong, are actually molecules. I'm saying that sodium, a poisonous element by itself, does the same thing in table salt, something you can eat without dying.


Something tells me you haven't taken biology.

This isn't just "oh hey salt is made of two poisonous things" this is a COMPLETELY DIFFERENT ELEMENT in an animal's DNA


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## Lucas₇₅₅ (Dec 4, 2010)

Something tells me you don't understand my point. 

Yeah, it's a big deal that there's a new element in DNA, but it seems to me that they're saying something along the lines of "A poisonous element in DNA? Wow!", when it's really in a molecule, so it's not necessarily poisonous.


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## opaltiger (Dec 4, 2010)

Lucas755 said:


> Something tells me you don't understand my point.
> 
> Yeah, it's a big deal that there's a new element in DNA, but it seems to me that they're saying something along the lines of "A poisonous element in DNA? Wow!", when it's really in a molecule, so it's not necessarily poisonous.


You are so confused I'm not sure where to start. :P It's not a case of arsenic being poisonous on its own but not in DNA. It's a matter of a bacterium not only tolerating arsenic but integrating it _into its biochemistry_.


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## Lucas₇₅₅ (Dec 4, 2010)

Well, I get that, but in all of the things I've read or heard (I didn't read this linked article), it sounded like they were making a big deal about something poisonous being in DNA, not about something new being in DNA, which is the real point of the story. Unless I'm missing something, which I definitely am.


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## Teh Ebil Snorlax (Dec 4, 2010)

The point is that normally, when arsenic interacts with living things, it kills the fuck out of them and even those that survive on it have their quality of life greatly decreased but these organisms actually use it to replace phosphorus, which totally averts the usual problems of interaction between arsenic and organisms.

That's why people are amazed that there are organisms making arsenic a part of their biochemistry; because usually it's toxic to organisms. That _is_ amazing.

And I don't know what you're reading but not reading anything linked on the last page might be your problem; the fact that there are living organisms that have a different chemical in their DNA is certainly the most amazing things, it's just made more amazing that the chemical in question is an almost-uniformly toxic chemical.


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## Kali the Flygon (Dec 5, 2010)

This isn't the first time life has found a way to thrive by using a previously-toxic chemical, so I'm not surprised. A long time ago, bacteria discovered the Aerobic cycle, utilizing oxygen for energy rather than expelling it as waste.

To be honest, methane and carbon dioxide seem to make up the atmosphere of most planets too small to retain pure hydrogen. One sign of possible life that scientists could look for is the presence of free oxygen as a significant portion of the planet's atmosphere.


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## Harlequin (Dec 9, 2010)

HM I might have to go to the science library and read the paper! I rarely do this because I'm lazy, but this is quite interesting! hurrah


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